TPSM8291x Step-Down Power Module Evaluation Module

1 TPSM8291xEVM Evaluation Module

The TPSM8291xEVM (BSR213) facilitates the evaluation of the TPSM8291x 2-A and 3-A pin-to-pin compatible low-noise (< 20 μV_RMS) and low-ripple (< 10 μV_RMS) buck power modules in small 4.5-mm by 5.5-mm QFN packages. The BSR213-001 uses the 3-A TPSM82913 to output a 1.2-V output voltage from input voltages between 3 V and 17 V. The BSR213-002 uses the 2-A TPSM82912 to output a 3.3-V output voltage from input voltages up to 17 V. Due to its extremely low noise, the TPSM8291x is a high-efficiency alternative to low-dropout (LDO) linear regulators in noise-sensitive circuits, such as data converters, clocks, and amplifiers in telecom infrastructure, medical, test and measurement, and aerospace and defense applications.

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1 Introduction

The TPSM8291x family of devices are low-noise, low-ripple, synchronous, step-down power modules in a small 4.5-mm × 5.5-mm × 1.8-mm QFN package. Two different devices in this family support 2 A or 3 A of output current.

1.1 Performance Specification

Table 1-1 and Table 1-2 provides a summary of the TPSM8291xEVM performance specifications.

Table 1-1 TPSM82913EVM Performance Specification Summary

SPECIFICATION	TEST CONDITIONS	MIN	TYP	MAX	UNIT
Input voltage	JP2 open or across 1 MHz and S-CONF	3	12	17	V
Output voltage setpoint			1.2		V
Output current		0		3	A
S-CONF (R7) setting	1 MHz with SYNC available, no spread spectrum, output discharge enabled		52.3		kΩ

Table 1-2 TPSM82912EVM Performance Specification Summary

SPECIFICATION	TEST CONDITIONS	MIN	TYP	MAX	UNIT
Input voltage		3.5	12	17	V
Output voltage setpoint			3.3		V
Output current		0		2	A
S-CONF (R7) setting	2.2 MHz with SYNC available, no spread spectrum, output discharge enabled		27.4		kΩ

1.2 Modifications

The printed-circuit board (PCB) for this EVM is designed to accommodate some modifications by the user. Additional input and output capacitors can be added. Also, the input voltage at which the IC turns on can be adjusted with two resistors, the soft-start time and low frequency noise filtering can be changed, a feedforward capacitor can be added, and the switching frequency, output discharge setting, and spread spectrum setting can be changed. See the device TPSM8291x 3-V to 17-V, 2-A/3-A Low Noise and Low Ripple Buck Power Module with Integrated Ferrite Bead Filter Compensation data sheet for details of the various settings.

1.2.1 Input and Output Capacitors

C4 is provided for an additional input capacitor. This capacitor is not required for proper operation but can be used to reduce the input voltage ripple.

C10, C14, and C15 are provided for additional bulk output capacitors. These capacitors are not required for proper operation but can be used to reduce the output voltage ripple. The total output capacitance must remain within the recommended range in the TPSM8291x 3-V to 17-V, 2-A/3-A Low Noise and Low Ripple Buck Power Module with Integrated Ferrite Bead Filter Compensation data sheet for proper operation. C11 and C16 are provided for high-frequency bypass capacitors.

1.2.2 Configurable Enable Threshold Voltage

With J5 removed, R3 and R5 can be installed to set a user-selectable input voltage at which the IC turns on.

1.2.3 NR/SS Capacitor

There is an internal soft-start capacitor that sets the default start up time and filtering for the NRSS pin. C18 allows the addition of more capacitance to increase the soft-start time and the low frequency noise filtering.